launcher reads:

Bootstrap (v5)
Current time is Apr 23, 2014 6:13:06 PM
System.getProperty('os.name') == 'Windows 8'
System.getProperty('os.version') == '6.2'
System.getProperty('os.arch') == 'x86'
System.getProperty('java.version') == '1.7.0_55'
System.getProperty('java.vendor') == 'Oracle Corporation'
System.getProperty('sun.arch.data.model') == '32'

Looking for update
Downloading: https://s3.amazonaws.com/Minecraft.Download/launcher/launcher.pack.lzma
Got reply in: 324ms
No update found.
Reversing LZMA on C:\Users\Home\AppData\Roaming\.minecraft\launcher.pack.lzma to C:\Users\Home\AppData\Roaming\.minecraft\launcher.pack
Unpacking C:\Users\Home\AppData\Roaming\.minecraft\launcher.pack to C:\Users\Home\AppData\Roaming\.minecraft\launcher.jar
FATAL ERROR: net.minecraft.bootstrap.FatalBootstrapError: Unable to un-pack200: java.io.FileNotFoundException: C:\Users\Home\AppData\Roaming\.minecraft\launcher.jar (Access is denied)
at net.minecraft.bootstrap.Bootstrap.unpack(Bootstrap.java:159)
at net.minecraft.bootstrap.Bootstrap.execute(Bootstrap.java:123)
at net.minecraft.bootstrap.Bootstrap.main(Bootstrap.java:381)

Please fix the error and restart.